The manolo boards are very flat thru the tail, less than 1/2cm tail kick, which planes up quick, and the small tail area means minium drag once planing fast(more surface area creates drag)..
I have a 147 wavetray and a 5ft 6" underground directional, and hands down, the directional is faster, and points much higher upwind, while requiring far less wind. (mostly due to the extra speed you get out it = more apparent wind speed) The wavetray can go pretty fast in control to almost match the speed of the directional if you try, but you go downwind to acheive this!! Just an additional note, my directional has a lot more rocker and tail kick than a Manolo, but for all intents and purposes has the same speed/upwind capability in small-large chop conditions that we get in NZ, but in dead flat water I guess than flat Manolo could have an advantage.

If you edge into the wind, like in kiteboarding, with the "edge" of the board, the less rocker you have, the more drag in the water. This is why windsurfers typically go faster than a kitesurfer.

Too many fins cause drag, yes, but not enough promotes drag, as well, by forcing you to dig your board in the water deeper. There's more to shaping boards than bending plywood.

Bonzer bottoms, channels, etc. are all developed to release pressure from the board, as well. The board tends to "stick" to the water from surface tension. If you hold the back of a spoon to running water from a faucet, the water will bend along the spoon. The water pushes on the spoon, and the spoon "pulls" on the water. The wakeboard-style kiteboards require more edge to go upwind due to smaller fins, and you can boost higher, due to the harder edge. Directionals are faster with a round edge but more fins and typically boost highest. Bidirectionals and mutants are kinda the "best of both worlds", but you sacrifice in style and function depending on your riding style. In the end, its all personal preference, but the board's shape affects the ride quite a bit.

I'm 90 kgs and I ride my Hydro 13 (real area 17.8 ) with a Wipika Eclipse 159. It's an easy and performing board,another good choice could be RRD Airtrixx 160,then some days ago I tried my friend's RADICAL TT/WAKE;it's a custom and I think it's the best board on the market.
P.S. This is the board that Cattelan and Sudrat use.
You can see it at http://www.radical.fr